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1991 S10 fuel pump issue please help
02-17-2014, 11:16 PM
Post: #2
RE: 1991 S10 fuel pump issue please help
8.5 volts is not enough to run anything. At that age I suspect poor connections. I would start with a fully charged battery then go to cleaning all cable ends, especially the ground end from the battery to the radiator support. (common issue on a 4.3) Next look at the ground wire that's on the stud at the t-stat housing. If that's not clean it will not start. There's also a ground breaking out of the wiring harness going back to the fuel tank. It goes to a screw on the frame rail near the tank. If all else fails see what the voltage is at the battery. Should be 12.6 or slightly higher. There should be no more than a half volt drop anywhere in the system. If it's more then you need to do some detective work.

Some years had several fuses for the system marked ECM1, ECM2, and fuel pump. They all need to be good!

BTW, that ground on the radiator support is also for the headlights and there may be a second one on the other side of the radiator. On some there's yet another ground on the firewall near the heater case. It's too long ago to say exactly what years / model had that. As I recall, if it goes bad the blower motor also doesn't work. Old vehicles and poor connections go hand in hand.

Let us know what you find.
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RE: 1991 S10 fuel pump issue please help - Rupe - 02-17-2014 11:16 PM

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